Suspension and lock-out systems for a partially tracked vehicle

ABSTRACT

A partially tracked utility vehicle and conversion are provided. The converted partially tracked utility vehicle has a chassis, front wheels, and a trailing link suspension. The trailing link suspension has a trailing link with a first end pivotably connected to said chassis and a second end pivotably connected to a walking beam at a walking beam pivot; a shock having a first end pivotably connected to a tension shaft and a second end pivotably connected to said trailing link; said walking beam further comprising a plurality of axle mounted bogey wheels for engaging a track of said partially tracked utility vehicle; a sprocket mounted to a traction drive of said utility vehicle for engaging and providing rotational power to said track; and an actuator attached to said chassis, said actuator having a shaft pivotably connected to said tension shaft and configured to rotate said tension shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 61/877,556, filed Sep. 13, 2013, and entitled “SUSPENSION ANDLOCK-OUT SYSTEMS FOR A PARTIALLY TRACKED VEHICLE”, which is hereinincorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to a garden or lawn utility vehicle,and more particularly, to a suspension system for a garden or lawnutility vehicle having a partially tracked propulsion system.

BACKGROUND OF THE INVENTION

A tracked vehicle's weight is transferred to the bottom length of trackby a number of road wheels, or sets of bogie wheels. Road wheels arefrequently mounted on some form of suspension to cushion the ride overrough ground. Suspension design in military vehicles is a major area ofdevelopment, and the very early designs were often completely un-sprung.Later-developed road wheel suspension offered only a few inches oftravel using springs, whereas modern hydro-pneumatic systems can provideseveral feet of travel and typically incorporate shock absorbers.Torsion-bar suspension is probably the most common type of militaryvehicle suspension. Construction vehicles have smaller road wheels thatare designed primarily to prevent track derailment, and they arenormally contained within a single bogie that integrates the idler wheeland sometimes the drive sprocket.

Track drive suspensions are inherently faced with performance issueswhich include limited travel/effective suspension, track derailment, andrestricted/limited utilization of attachments. These limitations have adirect effect on machine directional/steering control, ride quality,flexibility/functionality with attachments, stability and travel speed.

Transfer of power to the tracks is accomplished by drive wheels(friction), or drive sprockets, that are powered by transmissions ormotors that engage holes or lugs in the track links that drive thetrack. In military vehicles, the drive wheel is typically mounted wellabove the contact area on the ground, allowing it to be fixed inposition. In agricultural and construction tracked vehicles, the drivewheel is normally incorporated as part of the bogie. Placing suspensionon the drive sprocket is possible, but is mechanically more complicated.A non-powered wheel, an idler, is placed at the opposite end of thetrack, primarily to tension the track—loose track could be easily thrown(slipped) off the wheels. To prevent throwing, the inner surfaces of thetracks usually have vertical guide lugs engaging gaps between the bogieand idler/sprocket wheels. In military vehicles with a rear sprocket,the idler wheel is placed higher than the road wheels to allow it toclimb over obstacles. Some track arrangements use return rollers to keepthe top of the track running straight between the drive sprocket andidler. Others, called slack track, allow the track to droop and runalong the tops of large bogie (sometimes called road) wheels. This was afeature of the Christie suspension, leading to occasionalmisidentification of other slack track-equipped vehicles. Many WW IIGerman military vehicles, including all half-track and all later tankdesigns (after the Panzer IV), had slack-track systems, usually drivenby front-located drive sprockets, running along the tops of the oftenoverlapping, and sometimes interleaved, large diameter doubled roadwheels (on the Tiger I and Panther, in their suspension systems). Thechoice of overlapping/interleaved road wheels allowed the use ofslightly more torsion bar suspension members, allowing any Germantracked military vehicle with such a setup to have a noticeably smootherride over challenging terrain, but at the expense of mud and icecollecting between the overlapping areas of the road wheels, andfreezing solid in cold weather conditions, often immobilizing thevehicle so equipped.

It takes considerable power to steer a tracked vehicle. As the vehicleturns, the leading and trailing ends of the footprint, or contact patch,skid sideways, perpendicular to the direction the tracks roll. Hence thename “skid steering” could be applied.

In FIG. 1, the arrows indicate the direction in which the contact patchwill move during a right (clockwise) neutral axis (Zero) turn. A neutralaxis (Zero) turn is a turn about a center point through the machine orthe powered drive axle. The further toward the ends, the more the trackwill move in a direction other than the direction in which it wouldnormally move for forward propulsion.

FIG. 2 shows the magnitude of the frictional forces that must beovercome in order to make the vehicle turn about its vertical axis.These are simply the horizontal component of the direction that eachpoint of the contact patch will move as the vehicle rotates. Thefriction at any point is proportional to the distance forward of thevertical axis. From this it follows that the total force required isproportional to the length of the contact patch, the weight of thevehicle, and the inverse of the radius of the turn.

The worst-case scenario for overcoming friction is the pivot turn. Apivot turn is a turn about a center point through the center of a“stationary” traction track. In a pivot turn, in which one track travelsin a direction while the other track stays stationary, which results inthe vehicle rotating about a center point through the center of a“stationary” traction track.

Further, turns executed while both tracks are traveling generallyrequire less power, as less energy is required to overcome the staticfriction associated with a travelling track, as opposed to a statictrack. Also, apart from the pivot turn, when compared to the zero turn,turns of greater radii will require less power, as the energy requiredto overcome the static friction (or terrain abrasion) is spread out overa longer period of time.

Therefore, a need exists for an improved suspension system for trackedvehicles.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, a trailing link suspension for a trackedutility vehicle having a chassis comprises: a forward trailing linkhaving a first end pivotably connected to the chassis and a second endpivotably connected to a forward walking beam at a walking beam pivot; aforward shock having a first end pivotably connected to the chassis anda second end pivotably connected to the forward trailing link; a reartrailing link having a first end pivotably connected to the chassis anda second end pivotably connected to a rear walking beam at a walkingbeam pivot; a rear shock having a first end pivotably connected to thechassis and a second end pivotably connected to the rear trailing link;an intermediate trailing link located between the forward tailing linkand the rear trailing link; the intermediate trailing link having afirst end pivotably connected to the chassis and a second end pivotablyconnected to an intermediate walking beam at a waling beam pivot; thewalking beams having a plurality of axle mounted bogey wheels forengaging a track of the tracked utility vehicle.

In another aspect of the invention, at least one of the trailing linksfurther comprises a lock-out. In another aspect of the invention, thelock-out is a pneumatic lock-out comprised of the shock. In anotheraspect of the invention, the lock-out is a mechanical lock-out comprisedof a mechanical lock-out member. In another aspect of the invention, thelock-out member further comprises a first end pivotably connected to thechassis and a second end selectively connected to the trailing link.

In another aspect of the invention, at least one of the walking beammembers has a pan-hard rod comprised of a rigid rod having a first endand a second end; the first end is pivotably connected to the walkingbeam member and the second end is pivotably connected to the chassisopposite the walking beam.

In another aspect of the invention, the walking beam pivot of at leastone walking beam is biased toward a front or a rear of the trackedutility vehicle. In another aspect of the invention, the walking beampivot of the front walking beam is biased toward the front of thetracked utility vehicle, and the walking beam pivot of the rear walkingbeam is biased toward the rear of the tracked utility vehicle. Inanother aspect of the invention, the walking beam pivot of the frontwalking beam is biased toward the front of the tracked utility vehicle,and the walking beam pivot of the rear walking beam is biased toward thefront of the tracked utility vehicle. In another aspect of theinvention, the walking beam pivot of the front walking beam is biasedtoward the rear of the tracked utility vehicle, and the walking beampivot of the rear walking beam is biased toward the rear of the trackedutility vehicle.

In another aspect of the invention, at least of the walking beams has aroll pivot, thereby permitting all of the bogey wheels of the walkingbeam to maintain contact with the track on uneven terrain. In anotheraspect of the invention, the roll pivot is located below the walkingbeam pivot and the axles of the walking beam.

In another aspect of the invention, the walking beam is furthercomprised of a forward section, a middle section, and a rear section;the forward section and the middle section are pivotably connected witha first roll pivot; the rear section and the middle section arepivotably connected with a second roll pivot; the walking beam pivot issituated in the middle section; the forward section and the rear sectioneach have bogey wheels mounted on axels that engage at least one of thetrack, or a track lug or guide. In another aspect of the invention, theforward section and the rear section pivot independently. In anotheraspect of the invention, the first and second roll pivot movement islimited to about +/−10 degrees.

In another aspect of the invention, the trailing link is comprised of atleast one swing arm.

In another aspect of the invention, the trailing link is comprised of afirst swing arm and a second swing arm connected with an upper crossbrace and a lower cross brace.

In another aspect of the invention, the shocks are comprised of at leastone of coil, leaf or torsion springs; wherein the shocks are mechanical,hydraulic, and/or pneumatic.

In another aspect of the invention, the shocks are independentlyadjustable so that more of the tracked utility vehicle's weight issupported as a midpoint of the suspension.

In yet another aspect of the invention, a trailing link suspension for atracked utility vehicle having a chassis is comprised of at least twotrailing links, each of the trailing links having a shock and a walkingbeam; a first end of the trailing link is pivotably connected to thechassis and a second end of the trailing link is pivotably connected tothe walking beam; the shock has a first end pivotably connected to thechassis and a second end pivotably connected to the trailing link; thewalking beams having a plurality of axle mounted bogey wheels forengaging one or both of a track of the tracked utility vehicle or atrack lug or guide of the track; wherein the shocks are independentlyadjustable to permit more of the tracked utility vehicle's weight to besupported at a midpoint of the suspension.

In yet another aspect of the invention, a partially tracked utilityvehicle having a chassis is comprised of front wheels and a trailinglink suspension. The trailing link suspension is comprised of: atrailing link having a first end pivotably connected to the chassis anda second end pivotably connected to a walking beam at a walking beampivot; a shock having a first end pivotably connected to a tension shaftand a second end pivotably connected to the trailing link; the walkingbeam further comprising a plurality of axle mounted bogey wheels forengaging a track of the partially tracked utility vehicle; a sprocketmounted to a traction drive of the utility vehicle for engaging andproviding rotational power to the track; an actuator attached to thechassis, the actuator having a shaft pivotably connected to the tensionshaft and configured to rotate the tension shaft.

In another aspect of the invention, the partially tracked vehiclefurther comprises front wheels having a steerable axle.

In another aspect of the invention, the steerable axle of the partiallytracked vehicle is synchronized with the traction drive of the track toemulate Ackerman Steering geometry.

In another aspect of the invention, the rotation of the tension shaftincreases or decreases the tension of the tracks.

In another aspect of the invention, rotation of the tension shaftincreases or decreases the height of the partially tracked vehicle.

In another aspect of the invention, the partially tracked vehicle shockcan be configured to act as a lock-out member.

In another aspect of the invention, the walking beam pivot of thewalking beam is biased toward a front or a rear of the partially trackedutility vehicle.

In another aspect of the invention, the shock is comprised of at leastone of coil, leaf or torsion springs.

In another aspect of the invention, the shocks are mechanical,hydraulic, and/or pneumatic.

In another aspect of the invention, the partially tracked vehiclefurther comprises an attachment boom assembly having an boom and anattachment interface, the attachment boom assembly being pivotablyattached to the chassis.

In another aspect of the invention, the boom has a first end and asecond end, the boom first end is pivotably attached to the chassis andthe boom second end is pivotably attached to an attachment interface.

In another aspect of the invention, the attachment boom assembly furthercomprises at least one of a lift cylinder or a pitch cylinder. The liftcylinder being pivotably mounted between the chassis and the boom, andthe pitch cylinder being pivotably mounted between the boom and theattachment interface.

In yet another aspect of the invention, a utility vehicle conversion isprovided. The utility vehicle conversion includes tracks for a tractiondrive of a utility vehicle having a chassis. The utility vehicleconversion further comprises a trailing link having a first endpivotably connectable to the chassis and a second end pivotablyconnectable to a walking beam at a walking beam pivot; a shock having afirst end pivotably connectable to a tension shaft and a second endpivotably connectable to the trailing link; the walking beam furthercomprising a plurality of axle mounted bogey wheels for engaging atrack; and a sprocket mountable to a traction drive of the utilityvehicle for engaging and providing rotational power to the track.

In another aspect of the utility vehicle conversion, the utility vehicleconversion further comprises an actuator attachable to the chassis, theactuator having a shaft pivotably connected to the tension shaft andconfigured to rotate the tension shaft.

In another aspect of the utility vehicle conversion, the utility vehiclefurther comprises front wheels having a steerable axle. Further, thetraction drive of the track is synchronizable with the steerable axle toemulate Ackerman Steering geometry.

In another aspect of the utility vehicle conversion, the rotation of thetension shaft increases or decreases the tension of the tracks.

In another aspect of the utility vehicle conversion, wherein therotation of the tension shaft increases or decreases the height of theutility vehicle.

In another aspect of the utility vehicle conversion, the shock isconfigurable to act as a lock-out member.

In another aspect of the utility vehicle conversion, the walking beampivot of the walking beam is biased toward a front or a rear of theutility vehicle.

In another aspect of the utility vehicle conversion, the shock iscomprised of at least one of coil, leaf or torsion springs.

In another aspect of the utility vehicle conversion, the shocks aremechanical, hydraulic, and/or pneumatic.

In another aspect of the utility vehicle conversion, the utility vehicleconversion further comprising an attachment boom assembly having an boomand an attachment interface, the attachment boom assembly beingpivotably attachable to the chassis.

In another aspect of the utility vehicle conversion, the boom has afirst end and a second end, the boom first end is pivotably attachableto the chassis and the boom second end is pivotably attachable to anattachment interface pivotably attached.

In another aspect of the utility vehicle conversion, the attachment boomassembly further comprises at least one of a lift cylinder or a pitchcylinder; the lift cylinder being pivotably mountable between thechassis and the boom, the pitch cylinder being pivotably mountablebetween the boom and the attachment interface.

In yet another aspect of the invention, a utility vehicle conversion forproviding tracks for a right traction drive and a left traction drive ofa utility vehicle having a chassis is disclosed. The utility vehicleconversion comprises: a right trailing link having a first end pivotablyconnectable to a right side of the chassis and a second end pivotablyconnectable to a right walking beam at a walking beam pivot; a rightshock having a first end pivotably connectable to a tension shaft and asecond end pivotably connectable to the right trailing link; the rightwalking beam further comprising a plurality of axle mounted bogey wheelsfor engaging a right track; a right sprocket mountable to a righttraction drive mounted to the right side of the chassis for engaging andproviding rotational power to the track; a left trailing link having afirst end pivotably connectable to a left side of the chassis and asecond end pivotably connectable to a left walking beam at a walkingbeam pivot; a left shock having a first end pivotably connectable to atension shaft and a second end pivotably connectable to the lefttrailing link; the left walking beam further comprising a plurality ofaxle mounted bogey wheels for engaging a left track; and a left sprocketmountable to a left traction drive mounted to the left side of thechassis for engaging and providing rotational power to the track.

In another aspect of the utility vehicle conversion, the conversion iscomprised of an actuator attachable to the chassis, the actuator havinga shaft pivotably connected to the tension shaft and configured torotate the tension shaft.

In another aspect of the utility vehicle conversion, the utility vehiclefurther comprises front wheels having a steerable axle.

In another aspect of the utility vehicle conversion, the right and lefttraction drives of the right and left tracks are synchronizable with thesteerable axle to emulate Ackerman Steering geometry.

In another aspect of the utility vehicle conversion, the rotation of thetension shaft increases or decreases the tension of the tracks.

In another aspect of the utility vehicle conversion, the rotation of thetension shaft increases or decreases the height of the utility vehicle.

In another aspect of the utility vehicle conversion, at least one of theright shock or left shock is configurable to act as a lock-out member.

In another aspect of the utility vehicle conversion, the walking beampivot of at least one of the right walking beam or left walking beam isbiased toward a front or a rear of the utility vehicle.

In another aspect of the utility vehicle conversion, each of the rightshock and the left shock is comprised of at least one of coil, leaf ortorsion springs.

In another aspect of the utility vehicle conversion, wherein the rightshock is mechanical, hydraulic, and/or pneumatic.

In another aspect of the utility vehicle conversion, wherein the leftshock is mechanical, hydraulic, and/or pneumatic.

In another aspect of the utility vehicle conversion, the utility vehicleconversion further comprises an attachment boom assembly having an boomand an attachment interface, the attachment boom assembly beingpivotably attachable to the chassis.

In another aspect of the utility vehicle conversion, the boom has afirst end and a second end, the boom first end is pivotably attachableto the chassis and the boom second end is pivotably attachable to anattachment interface pivotably attached.

In another aspect of the utility vehicle conversion, wherein theattachment boom assembly is further comprised of at least one of a liftcylinder or a pitch cylinder, the lift cylinder being pivotablymountable between the chassis and the boom, and the pitch cylinder beingpivotably mountable between the boom and the attachment interface.

In yet another aspect of the invention, a method of converting a utilityvehicle to a partially tracked utility vehicle is provided. The methodcomprising: providing a utility vehicle having a rear drive wheelmounted on a traction drive and front wheels mounted on a chassis, atrailing link, a shock, a walking beam, a drive sprocket, and a track;removing the rear drive wheel from said traction drive; pivotablyconnecting a first end of the trailing link to the chassis and pivotablymounting a second end of the trailing link to the walking beam at awalking beam pivot, wherein the walking beam further comprising aplurality of axle mounted bogey wheels for engaging the track; pivotablyconnecting the first end of the shock to a tension shaft pivotablyconnected to the chassis, pivotably connecting the second end of theshock to the trailing link; mounting the drive sprocket to the tractiondrive; and placing the track around the drive sprocket and the walkingbeam, wherein the drive sprocket engages and provides rotational powerto the track.

In another aspect of the method, the providing step further includesproviding the an actuator; wherein the method further comprises mountingthe actuator to the chassis and pivotably connecting a shaft of theactuator to the tension shaft, such that the actuator is configured torotate the tension shaft.

In another aspect of the method, the providing step further comprisesproviding the tension shaft, wherein the tension shaft is pivotablyconnected to the chassis following the providing step.

In another aspect of the method, the front wheels have a steerable axle.

In another aspect of the method, Ackerman steering geometry is emulatedby synchronizing the traction drive of the track with the steerableaxle.

In another aspect of the method, the traction drive of the track issynchronized with the steerable axle, thereby emulating Ackermansteering geometry.

In another aspect of the method, the tension shaft is rotated toincrease or decrease the tension of the track.

In another aspect of the method, the tension shaft is rotated toincrease or decrease the height of utility vehicle chassis.

In another aspect of the method, the shock is configurable as a lock-outmember.

In another aspect of the method, the walking beam pivot of the walkingbeam is biased toward a front or a rear of the utility vehicle.

In another aspect of the method, the shock is comprised of at least oneof coil, leaf or torsion springs.

In another aspect of the method, the shock is mechanical, hydraulic,and/or pneumatic.

In another aspect of the method, the providing step is further comprisedof providing an attachment boom assembly having an boom and anattachment interface, and pivotably attaching the attachment boomassembly to the chassis.

In another aspect of the method, the boom has a first end and a secondend, wherein the boom first end is pivotably attached to the chassis andthe boom second end is pivotably attached to an attachment interface.

In another aspect of the method, the attachment boom assembly is furthercomprised of at least one of a lift cylinder or a pitch cylinder.

In another aspect of the method, the lift cylinder is pivotably mountedbetween the chassis and the boom.

In another aspect of the method, the pitch cylinder being pivotablymounted between the boom and the attachment interface.

In another aspect of the method, a mower deck is removed from anunderside of the chassis after the providing step.

In yet another aspect of the invention, a method of converting a utilityvehicle to a partially tracked utility vehicle is provided. The methodcomprises: providing a utility vehicle having front wheels and a righttraction drive with a right rear drive wheel mounted on a right side ofa chassis and a left traction drive with a left rear drive wheel mountedon a left side of the chassis, a right trailing link, a right shock, aright walking beam, a right drive sprocket, a right track, a lefttrailing link, a left shock, a left walking beam, a left drive sprocket,and a left track; removing the right rear drive wheel from the righttraction drive and the left rear drive wheel from the left tractiondrive; pivotably connecting a first end of the right trailing link tothe right side of the chassis and pivotably mounting a second end of theright trailing link to the right walking beam at a walking beam pivot,wherein the right walking beam further comprising a plurality of axlemounted bogey wheels for engaging the right track; pivotably connectinga first end of the left trailing link to the left side of the chassisand pivotably mounting a second end of the left trailing link to theleft walking beam at a walking beam pivot, wherein the left walking beamfurther comprising a plurality of axle mounted bogey wheels for engagingthe left track; pivotably connecting the first end of the right shock toa tension shaft pivotably connected to the right side of the chassis,pivotably connecting the second end of the right shock to the righttrailing link; pivotably connecting the first end of the left shock to atension shaft pivotably connected to the left side of the chassis,pivotably connecting the second end of the left shock to the lefttrailing link; mounting the right drive sprocket to the right tractiondrive; mounting the left drive sprocket to the left traction drive;placing the right track around the right drive sprocket and the rightwalking beam, wherein the right drive sprocket engages and providesrotational power to the right track; and placing the left track aroundthe left drive sprocket and the left walking beam, wherein the leftdrive sprocket engages and provides rotational power to the left track.

In another aspect of the method, the providing step further includesproviding the an actuator; wherein the method further comprises mountingthe actuator to the chassis and pivotably connecting a shaft of theactuator to the tension shaft, such that the actuator is configured torotate the tension shaft.

In another aspect of the method, the providing step further comprisesproviding the tension shaft, wherein the tension shaft is pivotablyconnected to the chassis following the providing step.

In another aspect of the method, the front wheels have a steerable axle.

In another aspect of the method, Ackerman steering geometry is emulatedby synchronizing the traction drive of the track with the steerableaxle.

In another aspect of the method, the traction drive of the track issynchronized with the steerable axle, thereby emulating Ackermansteering geometry.

In another aspect of the method, the tension shaft is rotated toincrease or decrease the tension of the tracks.

In another aspect of the method, the tension shaft is rotated toincrease or decrease the height of utility vehicle chassis.

In another aspect of the method, the shock is configurable as a lock-outmember.

In another aspect of the method, the walking beam pivot of the walkingbeam is biased toward a front or a rear of the utility vehicle.

In another aspect of the method, each of the shocks is comprised of atleast one of coil, leaf or torsion springs.

In another aspect of the method, wherein each of the shocks aremechanical, hydraulic, and/or pneumatic.

In another aspect of the method, the providing step is further comprisedof providing an attachment boom assembly having an boom and anattachment interface, and pivotably attaching the attachment boomassembly to the chassis.

In another aspect of the method, the boom has a first end and a secondend, wherein the boom first end is pivotably attached to the chassis andthe boom second end is pivotably attached to an attachment interface.

In another aspect of the method, the attachment boom assembly is furthercomprised of at least one of a lift cylinder or a pitch cylinder;wherein the lift cylinder is pivotably mounted between the chassis andthe boom, the pitch cylinder being pivotably mounted between the boomand the attachment interface.

In another aspect of the method, wherein a mower deck is removed from anunderside of the chassis after the providing step.

In yet another aspect of the invention, the utility vehicle is a utilitymachine, including, but not limited to a zero turn mower or a zero turntractor.

Advantages of the present invention will become more apparent to thoseskilled in the art from the following description of the embodiments ofthe invention which have been shown and described by way ofillustration. As will be realized, the invention is capable of other anddifferent embodiments, and its details are capable of modification invarious respects.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

These and other features of the present invention, and their advantages,are illustrated specifically in embodiments of the invention now to bedescribed, by way of example, with reference to the accompanyingdiagrammatic drawings, in which:

FIG. 1 is a force-direction diagram for a tracked utility vehicleexecuting a neutral axis (Zero) turn;

FIG. 2 is a force-magnitude diagram for a tracked utility vehicleexecuting a neutral axis (Zero) turn;

FIG. 3 is an exemplary embodiment of a suspension system for a trackedvehicle;

FIGS. 4-5 is an exemplary embodiment of a tracked utility vehiclesuspension system with a walking beam pivot biased forward;

FIG. 6 depicts an exemplary embodiment of a trailing arm, walking beam,shock, and bogey wheels of a tracked vehicle suspension system;

FIG. 7 depicts an exemplary embodiment of a trailing arm of a trackedvehicle suspension system;

FIG. 8 depicts an exemplary embodiment of a walking beam incorporatingan additional degree of freedom (roll);

FIG. 9 depicts a bogey wheels mounted to a non roll-pivot equippedwalking beam during a turn on flat terrain;

FIG. 10 depicts an exemplary embodiment of bogey wheels mounted to aroll-pivot equipped walking beam during a turn on flat terrain;

FIG. 11 depicts bogey wheels mounted to a non-roll-pivot equippedwalking beam during a turn on sloped terrain;

FIG. 12 depicts an exemplary embodiment of bogey wheels mounted to aroll-pivot equipped walking beam during a turn on sloped terrain;

FIGS. 13-15 depicts exemplary embodiments of a roll-pivot equippedwalking beam;

FIGS. 16-17 depicts exemplary embodiment of a walking beam having apan-hard rod;

FIGS. 18-19 depicts exemplary embodiments of a trailing link having amechanical lock-out or pneumatic lock-out;

FIG. 20 depicts an exemplary embodiment of a non-tracked utilityvehicle;

FIG. 21 depicts an exemplary embodiment of a partially tracked utilityvehicle;

FIG. 22 depicts an exemplary embodiment of a walking beam;

FIG. 23 depicts an exemplary embodiment of a traction drive;

FIG. 24 depicts an exemplary embodiment of a shock;

FIG. 25 depicts an exemplary embodiment of a trailing arm and walkingbeam;

FIG. 26 depicts the underside of an exemplary embodiment of a partiallytracked utility vehicle;

FIGS. 27-28 depict an exemplary embodiment of a tension bar and walkingbeam of a partially tracked vehicle; and

FIG. 29 depicts an exemplary embodiment of a partially tracked utilityvehicle.

It should be noted that all the drawings are diagrammatic and not drawnto scale. Relative dimensions and proportions of parts of these figureshave been shown exaggerated or reduced in size for the sake of clarityand convenience in the drawings. The same reference numbers aregenerally used to refer to corresponding or similar features in thedifferent embodiments. Accordingly, the drawing(s) and description areto be regarded as illustrative in nature and not as restrictive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about”, is not limited to the precise valuespecified. In at least some instances, the approximating language maycorrespond to the precision of an instrument for measuring the value.Range limitations may be combined and/or interchanged, and such rangesare identified and include all the sub-ranges stated herein unlesscontext or language indicates otherwise. Other than in the operatingexamples or where otherwise indicated, all numbers or expressionsreferring to quantities of ingredients, reaction conditions and thelike, used in the specification and the claims, are to be understood asmodified in all instances by the term “about”.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, or that the subsequentlyidentified material may or may not be present, and that the descriptionincludes instances where the event or circumstance occurs or where thematerial is present, and instances where the event or circumstance doesnot occur or the material is not present.

As used herein, the terms “comprises”, “comprising”, “includes”,“including”, “has”, “having”, or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article or apparatus that comprises a list of elements is notnecessarily limited to only those elements, but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus.

The singular forms “a”, “an”, and “the” include plural referents unlessthe context clearly dictates otherwise.

Turning to FIGS. 3-5, The Tracked Utility Vehicle's (TUV) weight istransferred from chassis 10 to the bottom length 81 of the tracks 80(that portion contacting the terrain) by trailing link 30 andwalking-beam 40 suspension elements incorporating sets of wheels calledbogies 84. Six (6) trailing link 30 and walking-beam 40 elements areused for the suspension to transfer the TUV suspended weight throughforty-eight (48) bogie wheels 84 onto the tracks 80 while cushioning theride over uneven and rough terrain. FIG. 3, depicts side of TUV havingone track 80. The other side of TUV has a second track that mirrors thetrack depicted in FIG. 3. In this embodiment, each track 80 of TUV hasthree (3) trailing link 30 and walking-beam 40 elements. Each walkingbeam element 40 has eight (8) bogie wheels.

Configurations are anticipated that incorporate more or less trailinglinks, walking beams, and bogie wheels, but in this example TUVsuspension 20, six (6) trailing links, six (6) walking beams, andforty-eight (48) bogie wheels are depicted.

Transfer of power to the tracks 80 in FIG. 3 is accomplished by drivesprockets 85, that are powered by transmissions or motors that engagelugs and guides 86 in the track 80. A non-powered wheel, a tensioningidler 83, is placed at the opposite end of the track 80 from drivesprocket 85, primarily to tension the track—loose track could be easilythrown (slipped) off the wheels. As is depicted in FIG. 3-5, thetrailing-link suspension is a design in which trailing links 30 areconnected between (and perpendicular to and forward of) the walking beam40 and the chassis 10. The trailing-link design uses just one trailinglink 30 and an adjustable shock 50 to locate the walking-beamslongitudinally and laterally. Each trailing link 30 has a first end 32pivotably connected to chassis 10 and a second end 33 pivotablyconnected to walking beam 40 at walking beam pivot 41. Further, eachtrailing link 30 also has a shock flange 37 close to second end 33.Trailing links can have a single swing arm design, such as depicted inFIG. 3, or a multiple swing arm design, such as is depicted in FIGS. 4and 5.

Further, in FIGS. 3-5, each shock 50 has a first end 51 and a second end52. The first end 51 is pivotably connected to chassis 10 at a chassisshock flange 15. The second end 52 is pivotably connected to trailinglink 30 at trailing link shock flange 37. The suspension rate of theshocks 50 are used to set the vehicle's ride-height (its location in thesuspension stroke). Shocks 50 can have coil, leaf, or torsion springs.Further, shocks 50 can be hydraulic and/or pneumatic spring devices. TheTUV has adjustable pre-load springs 53 to allow for suspensioncompensation during periods when additional temporary or permanentpayload weight is used (that could otherwise affect ride-height orcollapse the suspension). The shock 50 is configured so as to maintainbogie wheel 84 contact with the track 80. It is anticipated that thepreload of shock 50 can be non-adjustable, mechanically adjustable, orair adjustable. Further, it is anticipated that the spring rate anddampening of shock 50 can be fixed and dictated pneumatically, or can beadjustable via an air spring 56. Spring rate and dampening for airshocks can be made by changing the amount of air in air spring 56 viaair spring valve 54. To an extent, the drag created during turningmaneuvers can be minimized by concentrating the weight on the middle ofthe contact patch (where the sliding movement is smallest) by increasingthe spring rates and preload of the mid-section spring elements. Tracktension is established and maintained via the adjustable spring rates ofthe roller or separate track tensioning idler 83. Accordingly,suspension 20 includes mechanical (coil, leaf, torsion, etc.) springs 50and hydraulic or pneumatic spring devices 50 that are individuallyselected or adjusted so that the mid-sections of suspension 20 cansupport more of the TUV weight to reduce the lateral forces generatedduring turning maneuvers. The mid sections include intermediate walkingbeam(s) 40 c, and associated shock 50 c and trailing link 30 c.

The walking beam suspension 20 depicted in FIGS. 3-5 is particularlyuseful in off-road applications incorporating tracks, since it offersgreat lateral stability, ride comfort, and only tend to raise loadheight minimally when small changes in the terrain are encountered.Walking beams 40 are assemblies with a pivot point 41, about which thereare portions of the “beam” on each side. In this embodiment, a trailinglink 30 is pivotably connected to each walking beam 40 at the walkingbeam pivot point 41.

Each end of the walking beam 40 incorporates an axle 43 assemblycontaining four (4) bogie wheels 84 which provides eight (8) bogiewheels per walking beam 40. Pivoting (pitching) of the walking beams 40allow for track segment movements with bounce (jounce) and reboundforces being centralized and equalized (or proportioned) at the walkingbeam/trailing link pivot 41 generally with minimal reaction of trailinglink 30, even during large pitch movements of the walking beam 40. Insome embodiments, walking beams 40 may incorporate torsion or jounceelastomeric blocks to absorb shock and control pivot rotation (pitch).

As can be seen, FIG. 3 depicts the left side suspension 20 and chassis10 of TUV. As is described above, the left side suspension 20 has oneshock 50 per trailing link 30, namely forward shock 50 a, rear shock 50b, and one or more intermediate shock(s) 50 c located between forwardshock 50 a and rear shock 50 b. Further, the left suspension has onetrailing link 30 per walking beam 40, namely forward walking beam 20 a,rear walking beam 20 b, and one or more intermediate walking beam(s) 20c located between forward walking beam 20 a and rear walking beam 20 b.For the sake of brevity, it is understood that the right side suspension20 and chassis 10 of TUV is a mirror image of the left side suspension20 and chassis 10 described herein.

FIG. 6 is a close up depiction of a shock 50, trailing link 30, andwalking beam 40. Shock 50 has a first end 51 and a second end 52. Thefirst end 51 is pivotably connected to chassis 10 at a chassis shockflange 15. The second end 52 is pivotably connected to trailing link 30at trailing link shock flange 37. Preload of shock 50 is dictated by theload placed upon spring 53 by mechanical and air means. For hydraulicshocks, rough preload can be adjusted via pneumatic pressure throughpreload air valve 55 and an air pump, and finer preload adjustments canbe made mechanically by adjusting the position of collar 57. Formechanical shocks, preload adjustments can be made mechanically byadjusting the position of collar 57. For air shocks, preload can beadjusted via pneumatic pressure through preload air valve 55 and an airpump.

Further, FIG. 6 depicts trailing link 30 having multiple curved swingarms 31. In this embodiment, trailing link 30 has a first swing arm 31 aand a second swing arm 31 b connected together via an upper cross brace34 and a lower cross brace 35. The first end 32 of trailing link 30 ispivotably connected to chassis 10 at a chassis trailing link flange 16.The second end 33 of trailing link 30 is pivotably connected to walkingbeam 40 at walking beam pivot 41. Lower cross brace 35 has a shockflange 37 for connecting the second end 52 of shock 50 to trailing link30. Walking beam 40 is pivotably connected to trailing link 30 atwalking beam pivot 41. In the embodiment shown, walking beam has twoaxels 43, with each axel 43 having four bogey wheels 84. FIG. 7 is aclose-up depiction of trailing link 30 described above in conjunctionwith FIG. 6.

Turning back to FIGS. 3-6, biasing the walking beam pivot 41 of walkingbeam 40 toward one end or the other of walking beam 40 results in thesuspension reaction that the walking beam 40 transfers to the trailinglink 30 proportionally increasing in direct relationship to the decreasein distance between the bogie wheel axle 43 to the walking beam pivot41; this effectively provides different suspension rates in differenttrack segments. In FIG. 3, the walking beam pivot 41 of the walkingbeams 40 are not biased. In FIGS. 4-5, the walking beam pivot 41 of themost forward walking beam 40 a and rear walking beam 40 b are bothbiased toward the front of the TUV, and intermediate walking beam 40 cis neutral, which shifts the contact patch towards the front of TUV. Inanother embodiment, it is contemplated that the walking beam pivot 41 ofthe most forward walking beam 40 a and rear walking beam 40 b are bothbiased toward their respective ends, and this maximizes the effectivebottom length of track (increases floatation and reduces groundpressure).

Turing to FIG. 8, some embodiments of walking beam 40 incorporate anadditional degree of freedom (roll) so that walking beam 40 maintainsthe pitch function and restricts the yaw movements. By adding the rollfunction provided by roll-pivot 44, bogie wheels 84 on axels 43 maintaincontact with the tracks 80 and track lugs and guides 86 during instanceswhereby one or both tracks 80 engage a laterally positioned slope thatis substantially greater than that of the TUV. This is demonstrated inFIGS. 9-12. More specifically, FIG. 9 depicts bogey wheels 84 mounted toa non-roll-pivot equipped walking beam 40 during a turn on flat terrain.As can be seen, all four of the bogey wheels 84 depicted are able toengage track 80 or track lugs and guides 86 during the turn on flatterrain. FIG. 10 depicts bogey wheels 84 mounted to a roll-pivot 44equipped walking beam 40 during a turn on flat terrain. As can be seen,all four of the bogey wheels 84 depicted are able to engage track 80 ortrack lugs and guides 86 during the turn on flat terrain.

FIG. 11 depicts bogey wheels 84 mounted to a non-roll-pivot equippedwalking beam 40 during a turn on sloped terrain. As can be seen, onlytwo of the four bogey wheels 84 depicted are able to engage track 80 ortrack lugs and guides 86 during the turn on sloped terrain. FIG. 12depicts bogey wheels mounted to a roll-pivot equipped walking beamduring a turn on sloped terrain. As can be seen, all four of the bogeywheels 84 depicted are able to engage track 80 or track lugs and guides86 during the turn on sloped terrain.

From the attached figures, it is apparent that on some slopes, only two(2) or possibly four (4) of eight (8) bogie wheels of walking beam 40could be engaging the track 80 or lugs and guides 86 on the tracks 80,which could cause the lugs and guides 86 to deform and allow the bogiewheels 84 to slide over the lugs and guides 86 creating a derailment oftrack 80. This condition of track derailment is prevented by includingroll-pivot 44 in walking beams 40, such as that depicted in FIG. 13,which would permit all the bogie wheels 84 on axels 43 to remain incontact with the track 80 and/or lugs and guides 86 so as to share theloading and minimize deformation of guide lug 86.

Turning to FIGS. 8 and 13-15, it can be seen that in some embodiments,the axis for roll pivot 44 is placed below the walking beam pivot 41axis and bogie wheel axles 43 in order to enhance stability. Further, insome embodiments, stability is further increased by having a roll pivot44 between forward section 46 and middle section 45 of walking beam 40,and having another roll pivot 44 between rear section 47 and middlesection 45 of walking beam 40. This allows forward section 46 and rearsection 47 to independently pivot at different angles from each other,which increases stability on terrain having quickly changing angles.

In additional embodiments, the roll pivot 44 movement is limited toabout +/−10 degrees.

Turning to FIGS. 16-17, pan-hard rods 60 can be used to stabilize thetrailing links 30 and to prevent lateral movement of the walking beams40, but the trailing links 30 can also be designed to minimize lateraldeflections, such as by employing multiple swing arms on a trailing link30. Each pan-hard rod 60 has a rigid rod 63 oriented in the same generalorientation as the bogie axles 43 (perpendicular to walking beam 40).Pan-hard rod 60 has a pivot on a first end 61 and a pivot on a secondend 62. Pivots on first end 61 and second end 62 can be spherical rodends or similar devices which connect to walking beam 40 and chassis 10on the opposite side of TUV from walking beam 40.

Looking at FIGS. 16 and 17, it can be seen that first end 61 of pan-hardrod 60 is connected to pan-hard rod flange 42 of walking beam 40.Further, FIG. 17 depicts two pan-hard rods 60, and demonstrates howfirst end 61 of pan-hard rod 60 connects to walking beam 40 on one sideof TUV, and second end 62 of pan-hard rod 60 connects to pan-hard rodflange 13 of chassis 10 on the opposite side of TUV from walking beam40. The Pan-hard rods permit movement upwards and downwards only in thevertical plane. There are tremendous de-tracking forces developed on thebogie wheels/walking-beams during TUV turning maneuvers. Yaw reactionsof the walking beams 40 are resisted by the trailing links 30 (and thepan-hard rods 60 if used due to the attachment location of the rods 60to the walking beams 40).

As depicted in FIGS. 18-19, some embodiments of suspension 20 alsoinclude a trailing link lock-out, such as a pneumatic trailing linklock-out, using pneumatic shock 50, or mechanical trailing linklock-out, using mechanical lock-out member 70, to reduce or minimizesuspension reactions, such as reducing TUV duck-bobbing (frontsuspension of TUV oscillating up and down) when the front of TUV isequipped with a heavy implement that extends beyond the footprint oftracks 80.

A mechanical trailing link lock-out is achieved using a mechanicallock-out member 70 having a first end 71, which is pivotably attached tochassis 10, and a second end 72. Second end 72 selectively attaches tomechanical lock-out storage flange 14 of chassis 10 or selectivelyattaches to mechanical lock-out flange 36 of trailing link 30.Accordingly, when mechanical lock-out member 70 is engaged, second end72 is attached to mechanical lock-out flange 36 of trailing link 30,thereby reducing or minimizing suspension reactions by holding trailinglink 30 stationary. However, when mechanical lock-out member 70 is notengaged, second end 72 is attached to mechanical lock-out storage flange14 of chassis, thereby not limiting the travel of trailing link 30.

The pneumatic trailing link lock-out is achieved by varying the springrates of pneumatic and/or hydraulic springs of shock 50 such that thespring rates were set high enough that shock 50 functioned in a mannersimilar to a mechanical lockout member 70 (forward mechanical lockoutmember 70 a, rear mechanical lockout member 70 b, or intermediatemechanical lockout member(s) 70 c). It is anticipated that in someembodiments, one or more of forward trailing arm 30 a, rear trailing arm30 b, or intermediate trailing arm(s) 30 c can be mechanicallylocked-out pneumatically via shock 50 (forward shock 50 a, rear shock 50b, or intermediate shock(s) 50 c) or a mechanical lockout member 70(forward mechanical lockout member 70 a, rear mechanical lockout member70 b, or intermediate mechanical lockout member(s) 70 c).

The system includes a Utility Vehicle with a chassis 10, an OccupantProtection System, bench or bucket seating, a Spark or CompressionIgnition engine, hydrostatic (pumps and motors) traction-drive system,service and park brake systems, a steering system that controls thespeed and direction of the tracks based on steer-angle input, aspeed/directional control linkage, a suspension system and groundengaging tracks. The system can also include stored-energy devices,electric generator/alternators, and electric motors. The system can alsoinclude tracks 80 to support and transfer the loading of the machinethrough suspension elements to the terrain it traverses. The system canalso include suspension elements including mechanical (coil, leaf,torsion, etc.) springs 50 and hydraulic or pneumatic spring devices 50.The system can also include suspension elements including mechanical(coil, leaf, torsion, etc.) springs 50 and hydraulic or pneumatic springdevices 50 that are individually selected or adjusted so that themid-sections can support more of the machine weight to reduce thelateral forces generated during turning maneuvers. The system can alsoinclude manually or power adjustable suspension elements. The system canalso include trailing-links 30 to transfer vertical and lateral loading(mass and payload) of the machine chassis 10 to the walking-beams 40.The system can also include walking-beams 40 with the walking beampivots 41 biased toward one end or the other, and centered for the midsections, that transfer the vertical and lateral loading of the machinefrom the trailing-links 30 to the bogie wheels 84.

The system can also include walking beams 40 that limit yaw movements,but allow pitch and roll movements that maintain bogie wheel 84 contactwith the tracks 80. The system can also include bogie-wheels 84 thattransfer the vertical and lateral load reactions of the machine thatoccur during normal operations, turning maneuvers and side hilloperations, from the walking-beams 40 to the tracks 80. The system canalso include tracks 80 with drive and guide lugs 86 that transfer thevertical, lateral and longitudinal loading of the machine from thebogie-wheels 84 and drive sprockets 85 to the terrain, and this includesthe lateral reactions that occur during turning maneuvers and thetraction forces generated by the drive sprockets 85. The system can alsoinclude return rollers to keep the top of the track running straightbetween the drive sprocket 85 and idler 83. The system can also includePan-Hard rods 60 to control and transfer lateral force reactions,generated during side hill operation and turning maneuvers, from the TUVchassis to the trailing links 30 and walking beams 40. The system canalso include an adjustable spring-loaded system that maintains tracktension. The system can also include increased ground contact area(fore-and-aft) with lower ground pressure. The system can also include alow propensity for track derailment and operation at high travel speeds.The system can also include improved ride quality compared to othersuspension systems.

Further, turning to FIG. 20, utility vehicles 2, which encompassesutility vehicles and utility machines such as Zero-Turn-Mowers, aregenerally supported by pneumatic tires which produce ground contactpatches based on the construction of the tires and their internalpressures. Except for low-pressure pneumatic tires, ground contactpressures for these applications are approximately equivalent to theinternal inflation pressures of the pneumatic tires. These pneumatictires at pressures (generally 10 psi and greater) can limit tire-terraintraction, deformate the terrain, and reduce machine stability (tire rollin both lateral and longitudinal directions). As can be seen, utilityvehicle 2 has a chassis 10 with a right side 11 and a left side 12.

Turning to FIGS. 20-29, in an embodiment of this proposal, the rearpneumatic tires/wheels 94 used to provide traction drive are removedfrom utility vehicle 2, and replaced with endless tracks 80, drivesprocket 85, and suspension 20. The front axle assembly 96 with its'front caster or steerable wheel assemblies 93 are retained. Accordingly,the portion of the utility vehicle's weight that was formerlytransferred to the terrain via the rear tires 94 is now transferred tothe bottom length 81 of the tracks 80 (that portion contacting theterrain) by trailing link 30 and walking-beam 40 suspension elementsincorporating sets of wheels called bogies 84. One trailing link 30 andwalking-beam 40 element is used for the suspension 20 to transfer thesuspended weight through three to eight (3 to 8) bogie wheels 84 ontothe tracks 80 while cushioning the ride over uneven and rough terrain.Configurations are anticipated that incorporate more or less trailinglinks 30, walking beams 40, and bogie wheels 84, but in this exemplaryembodiment, two (2) trailing links, two (2) walking beams, and eight (8)bogie wheels are depicted, with one(1) trailing link, one (1) walkingbeam, and four (4) bogie wheels on each side of utility vehicle 2.

The trailing-link suspension 20 is a design in which links 30 areconnected between (and perpendicular to and forward of) the walking beam40 and the chassis 10. The trailing-link suspension 20 uses just oneswing-arm type trailing link 30 and an adjustable spring-shock 50 tolocate a walking-beam 40 longitudinally and laterally. There aretremendous de-tracking forces developed on the bogie wheels 84 andwalking-beams 40 during turning utility vehicle 2 maneuvers. Yawreactions of the walking-beams 40 are resisted by the trailing links 30.

Walking beam suspensions 20 are particularly useful in off-roadapplications incorporating tracks 80, since they offer great lateralstability, ride comfort, and only tend to raise load height minimallywhen small changes in the terrain are encountered. Walking beams 40 areassemblies with a pivot point 41 in a middle section 45, about whichthere is a forward section 46 and a rear section 47. Each of the forwardsection 46 and rear section 47 of the beam 40 incorporates an axle 43containing two (2) bogie wheels for a total of four (4) bogie wheels perwalking beam. Pivoting (pitching) forward section 46 and rear section 47of the beam 40 at pivot point 41 allow for track segment movements withbounce (jounce) and rebound forces being centralized and equalized (orproportioned) at the walking beam pivot 41, generally with minimaltrailing link 30 reaction, even during large pitch movements of thewalking beam 40. Walking beams 40 may incorporate torsion or jounceelastomeric blocks to absorb shock and control pivot rotation (pitch).

In some embodiments, pivot point 41 of the walking beam 40 is biasedtoward forward section 46 or rear section 47 of the beam 40. The biasingof pivot point 41 of walking beam 40 results in an increase of thesuspension reaction transferred by the walking beam to the trailing linkthat is directly proportional to the decrease in distance between bogiewheel axle 43 and walking beam pivot point 41. This effectively providesdifferent suspension rates in different track segments. In theembodiment of walking beam 40 depicted in FIG. 21, pivot point 41 ofwalking beam 40 is biased toward forward section 46, which maximizes theeffective bottom length 81 of track 80 (increases floatation and reducesground pressure).

Transfer of power to the tracks 80 is accomplished by drive wheelsprockets 85, that are powered by transmissions or motors (tractiondrives) 115 that engage holes or lugs 86 in/on the inner surface oftrack links that drive the track 80. Stated alternatively, the transferof power to the tracks 80 is accomplished by drive wheel sprockets 85,that are powered by traction drives 115 that engage holes or lugs 86in/on the inner surface of track 80. The walking-beam 40 is usedprimarily to tension the track 80 but also to provide limited suspensionas described above. The boogie wheels 84 serve as track tensioningidlers and the walking-beam 40 allows track 80 to climb over obstacles.

Turning to FIGS. 20-23, since it takes considerable power to steer atracked vehicle 2, in some embodiments, a steerable front axle 96 isutilized and it is synchronized with the traction drive transmissions ormotors 115 driving track 80, which emulates Ackermann Steering geometry.As the vehicle 2 turns, the leading and trailing ends of the trackfootprint, or contact patch, skid sideways, perpendicular to thedirection the tracks roll, such as is shown in and described above inconjunction with FIGS. 1-2.

For a neutral axis (or “zero’) turn, which typically requires as muchpower to execute as to travel at full speed without turning for trackedmachines 2, the steered front wheels 93 assist in this maneuver toreduce terrain deformation and power consumption. Turns of greater radiiwill require less power, as the energy required to overcome friction (orterrain abrasion) is spread out over a longer period of time.

As can be seen, FIGS. 20-29 depict the right side suspension 20 andchassis 10 of utility vehicle 20 (right side from perspective of utilityvehicle operator). For the sake of brevity, it is understood that theleft side suspension 20 components (shock 50, trailing link 30, walkingbeam 40) and chassis 10 of utility vehicle 2 are a mirror image of theright side being described. As was described above, the right sidesuspension 20 has one shock per trailing link 30. Further, the rightside suspension has one trailing link 30 per walking beam 40. It isunderstood that the right and left side trailing links 30 operateindependently from each other, which allows for more smooth travel overuneven terrain.

FIG. 24 is a close up depiction of shock 50, tension shaft 100 andtrailing link 30. Shock 50 has a first end 51 and a second end 52. Thefirst end 51 is pivotably connected to tension shaft 100 at tensionshaft shock flange 101. It is understood that a tension shaft shockflange 101 is present on the right side of tension shaft 100 for theshock 50 on right side suspension 20, and a separate tension shaft shockflange 101 is present on the left side of tension shaft 100 for theshock 50 on left side suspension 20. The second end 52 is pivotablyconnected to shock flange 37 of trailing link 30. Preload of shock 50 isdictated by the load placed upon spring 53 by mechanical and air means.As was stated above, for hydraulic shocks, rough preload can be adjustedvia pneumatic pressure through shock preload air valve and an air pump,and finer preload adjustments can be made mechanically by adjusting theposition of the collar. For mechanical shocks, preload adjustments canbe made mechanically by adjusting the position of the collar. For airshocks, preload can be adjusted via pneumatic pressure through preloadair valve 55 and an air pump.

In some embodiments, shock 50 can act as a pneumatic trailing linklock-out. Pneumatic trailing link lock-out can be achieved by varyingthe spring rates of pneumatic and/or hydraulic springs of shock 50 suchthat the spring rates are set high enough that shock 50 functions in amanner similar to a mechanical lockout member 70 described above.

FIG. 25-26 depicts trailing link 30 having a first end 32 and a secondend 33. In some embodiments, the first end 32 has a flange 38 pivotablyconnected to trailing link aperture 18 of chassis 10. In someembodiments, flange 38 of the right side and left side trailing links 30rotate about a common shaft seated in trailing link apertures 18 on theleft and right sides of chassis 10. In other embodiments, a separatefastener is used to pivotably connect the right side trailing linkflange 38 to the right side trailing link aperture 18, and a separatefastener is used to pivotably connect the left side trailing link flange38 to the left side trailing link aperture 18. In some embodiments, thesecond end 33 has an axle 39 that pivotably connects to walking beam 40at walking beam pivot 41 and acts as walking beam axle 43. In otherembodiments, second end 33 has a flange that pivotably connects towalking beam 40 at walking beam pivot 41. FIG. 26 once againdemonstrates how right side trailing link 30 and left side trailing link30 are not physically synchronized and pivot independently of oneanother.

FIGS. 27-28 depict tension shaft 100, which has a first end 100 apivotably mounted to the right side of chassis 10 at pivot shaftaperture 17, and a second end 100 b pivotably mounted to the left sideof chassis 10 at pivot shaft aperture 17. Tension shaft 100 has anactuator flange 102 that is pivotably connected to a distal end 105 ofshaft 104 of actuator 103. In some embodiments, a tension shaft actuatoradapter 106 pivotably connected to actuator flange 102 receives andpivotably connects distal end 105 to actuator flange 102. Actuator 103is fixed to chassis 10. Tension shaft 100 also has a shock flange 101that is spaced apart rotationally from actuator flange 102. Shock flange101 is pivotably connected to a first end 51 of shock 50, which isconnected to trailing link 30. Accordingly, the vertical distancebetween trailing link axle 39 (with associated walking beam 40) andchassis 10 can be changed by rotating tension shaft 100, which iscontrolled by actuator 103. Therefore, FIG. 28 shows trailing link 30 ina fully retracted position where actuator shaft 104 is fully extended,and FIG. 27 shows trailing link 30 in a fully extended position whereactuator shaft 104 is fully retracted. Retracting and extending trailinglink 30 also increases the tension of tracks 80 and increases the rideheight of vehicle 2. The position of actuator shaft 104 is usercontrolled via an actuator switch (not shown).

As was stated above, a shock flange 101 is provided for both right shock50 and left shock 50. In one embodiment, the right shock flange 101 a islocated between actuator flange 102 and tension shaft first end 100 a,and left shock flange 101 b is located between actuator flange 102 andtension shaft second end 100 b. Right shock flange 101 a and left shockflange 101 b are parallel with respect to each other. Right shock flange101 a and left shock flange 10 lb are spaced apart rotationally fromactuator flange 102 with respect to the axis of rotation of tensionshaft 100.

FIG. 29 depicts an attachment boom assembly that is present on someembodiments of vehicle 2. Attachment boom assembly 130 has a boom 138with a first end 138 a pivotably attached to chassis 10 and a second end138 b pivotably attached to attachment interface 135. Attachmentinterface 135 is configured to connect with a variety of implements(outdoor power equipment and chore machines and accessories, including,but not limited to a mower, show thrower, brush, blade, and bucket).Attachment boom assembly 130 has a lift cylinder 136 having a first end136 a pivotably connected to chassis 10 and a second end 136 b pivotablyconnected to boom 138. Lift cylinder controls the vertical height ofattachment interface 135 and any attached implement. Some embodiments ofboom assembly 130 have a pitch cylinder 137 having a first end 137 apivotably connected to boom 138 and a second end pivotably connected toattachment interface 135. Pitch cylinder 137 controls the pitch ofattachment interface 135 and any attached implement.

In another embodiment, also disclosed is a utility vehicle conversion 3as shown in FIG. 21 and described in conjunction with FIGS. 20-29, whichreplaces rear traction drive tires 94 of utility vehicle 2 (and anyother parts that interfere with tracks 80 and suspension 20, such asdeck 95). For the sake of brevity, this utility vehicle conversion willbe described with respect to the suspension components 20 and chassis 10on the right side of utility vehicle 2. It is understood that the leftside suspension components 20 and chassis 10 of utility vehicle 2 willbe a mirror image of the right side described herein. The utilityvehicle conversion 3 provides tracks 80 for a traction drive 115 of autility vehicle 2 having a chassis 10. The utility vehicle conversion 3has a trailing link 30 with a first end 38 pivotably connectable to thechassis 10 and a second end 39 pivotably connectable to a walking beam40 at a walking beam pivot 41.

Further provided in utility vehicle conversion 3 is a shock 50 having afirst end 51 pivotably connectable to a tension shaft 100 and a secondend 52 pivotably connectable to the trailing link 30. Shock 50 iscomprised of at least one of coil, leaf or torsion springs; wherein theshocks are mechanical, hydraulic, and/or pneumatic. In some embodiments,shock 50 can be configured to act as a lock-out member.

The walking beam 40 has a plurality of axle mounted bogey wheels 84 forengaging the lugs 86 on the interior of track 80. In some embodiments,pivot point 41 of walking beam 40 is biased toward the front or rear ofutility vehicle 2. A drive sprocket 85 mountable to a traction drive 115of the utility vehicle 2 is configured to engage and provide rotationalpower to the track 80.

When not already present on utility vehicle 2, the utility vehicleconversion 3 also include an actuator 103 attachable to the chassis 10.The actuator 103 has a shaft 104 with a distal end 105 pivotablyconnected to the tension shaft 100 and configured to rotate the tensionshaft 100. The rotation of tension shaft 100 increases or decreases thetension of tracks 80 and the height of utility vehicle 2 and chassis 10.

Further, some embodiments of utility vehicle conversion 3 also includefront wheels 93 having a steerable axle 96, when present on utilityvehicle 2. Some embodiments of utility conversion 3 also have asynchronization of the steerable axle 96 with traction drive 115 for thetrack 80, which emulates Ackerman Steering geometry.

Some embodiments of utility vehicle conversion 3 further comprise anattachment boom assembly 130 that is pivotably attachable to chassis 10.Attachment boom assembly has a boom 138 and an attachment interface 135.Boom 138 has a first end 138 a and a second end 138 b, the boom firstend 138 a is pivotably attachable to the chassis 10 and the boom secondend 138 b is pivotably attachable to an attachment interface 135.Further, some embodiments of attachment boom assembly 138 furthercomprise one or both of lift cylinder 136 or pitch cylinder 137. Thelift cylinder 136 is pivotably mountable between the chassis 10 and theboom 138. The pitch cylinder 137 is pivotably mountable between the boom138 and the attachment interface 135.

Also disclosed is a method of converting a utility vehicle 2 to apartially tracked utility vehicle 2. For the sake of brevity, thismethod will be described with respect to the suspension components 20and chassis 10 on the right side of utility vehicle 2. It is understoodthat the left side suspension components 20 and chassis 10 of utilityvehicle 2 will be a mirror image of the right side described herein. Themethod includes providing a utility vehicle 2 having a rear drive wheel94 mounted on traction drive 115 and front wheels 93 mounted on achassis 10, a trailing link 30, a shock 50, a walking beam 40, a drivesprocket 85, and a track 80. This method includes removing rear drivewheel 94 from traction drive 115. If a mower deck 95 is present on theunderside of the utility vehicle 2 and interferes with any suspensioncomponents (such as track 80 or trailing link 30), this method furtherincludes removing the mower deck 95. The method also includes pivotablyconnecting a first end 38 of the trailing link 30 to the chassis 10 andpivotably mounting a second end 39 of the trailing link 30 to thewalking beam 40 at walking beam pivot 41. Walking beam 40 furtherincludes a plurality of axle mounted bogey wheels 84 for engaging thelugs 86 on the inner surface of track 80. Some embodiments of the methodinclude, biasing walking beam pivot 41 toward a front or a rear of theutility vehicle 2.

The method also includes pivotably connecting the first end 51 of theshock 50 to a tension shaft 100 pivotably connected to the chassis 10,and pivotably connecting the second end 52 of the shock 50 to thetrailing link 30. In some embodiments of the method, shock 50 can beconfigured as a lock-out member. In some embodiments, shock 50 iscomprised of at least one of coil, leaf or torsion springs. Further, insome embodiments, shock 50 is mechanical, hydraulic, and/or pneumatic.

Further included is mounting the drive sprocket 85 to the traction drive115. Additionally, the method includes, placing the track 80 around thedrive sprocket 85 and the walking beam 40, wherein the drive sprocket 85engages and provides rotational power to the track 80.

Some embodiments of the method further provide an actuator 103 formounting on chassis 10, if actuator 103 is not already present onutility vehicle 2, and pivotably connecting a distal end 105 of shaft104 of the actuator 103 to the tension shaft 100. Actuator 103 isconfigured to rotate the tension shaft 100. The rotation of tensionshaft 100 increases or decreases the tension of track 80 and/orincreased or decreases the ride height of utility vehicle chassis 10.

In some embodiments of the method, tension shaft 100 is also providedand pivotably connected to chassis 10, if not already present on utilityvehicle 2.

In some embodiments, utility vehicle 2 front wheels 93 are casters, inother embodiments, front wheels 93 are steerable with a steerable axle96. In some embodiments of utility vehicle 2 with front wheels 93 havinga steerable axle 96, Ackerman steering geometry is emulated bysynchronizing the traction drive 115 of the track 80 with the steerableaxle 96.

In some embodiments of the method of converting, an attachment boomassembly 130 is provided having a 138 boom and an attachment interface135. The attachment boom assembly 130 is then pivotably attached tochassis 10. In some embodiments, attachment boom assembly 130 ispivotably attached to chassis 10 by attaching a first end 138 a of theboom 138 to chassis 10. The second end of boom 138 b is then pivotablyattached to attachment interface 135. In some embodiments, attachmentboom assembly 130 has one or both of a lift cylinder 136 or a pitchcylinder 137. When present, lift cylinder 136 is pivotably mountedbetween the chassis 10 and the boom 138. When present, pitch cylinder137 is pivotably mounted between the boom 138 and the attachmentinterface 135.

This proposal includes a Utility Vehicle 2 with a chassis 10, anOccupant Protection System 120, bench or bucket seating 121, a Spark orCompression Ignition engine, hydrostatic (pumps and motors)traction-drive system 115, service and park brake systems, a steeringsystem that controls the speed and direction of the tracks based onsteer-angle input, a speed/directional control linkage, a suspensionsystem 20 and ground engaging tracks 80. This proposal can also includea Utility Vehicle 2 stored-energy devices, electricgenerator/alternators, and electric motors. This proposal can alsoinclude a Utility Vehicle 2 with tracks 80 to support and transfer aportion of the loading of the machine through suspension elements to theterrain it traverses. This proposal can also include a Utility Vehicle 2with suspension elements 20 including mechanical (coil, leaf, torsion,etc.) springs 50 and hydraulic or pneumatic spring devices 50. Thisproposal can also include a Utility Vehicle 2 suspension elements 20including mechanical (coil, leaf, torsion, etc.) springs 50 andhydraulic or pneumatic spring devices 50 that are manually or poweradjustable. This proposal can also include a Utility Vehicle 2 withmanually or power adjustable suspension elements 20. This proposal canalso include a Utility Vehicle 2 with trailing-links 30 to transfervertical and lateral loading (mass and payload) of the machine chassis10 to the walking-beams 40. This proposal can also include a UtilityVehicle 2 with walking-beams 40 with the walking beam pivots 41 biasedtoward one end or the other that transfer the vertical and lateralloading of the machine from the trailing-links 30 to the bogie wheels84.

This proposal can also include a Utility Vehicle 2 with bogie-wheels 84that transfer the vertical and lateral load reactions of the machinethat occur during normal operations, turning maneuvers and side hilloperations, from the walking-beams 40 to the tracks 80. This proposalcan also include a Utility Vehicle 2 with tracks 80 having drive andguide lugs 86 that transfer the vertical, lateral and longitudinalloading of the machine from the bogie-wheels 84 and drive sprockets 85to the terrain, and this includes the lateral reactions that occurduring turning maneuvers and the traction forces generated by the drivesprockets 85. This proposal can also include a Utility Vehicle 2 with anadjustable spring-loaded system that maintains track tension. Thisproposal can also include a Utility Vehicle 2 with increased groundcontact area (fore-and-aft) with lower ground pressure.

While this invention has been described in conjunction with the specificembodiments described above, it is evident that many alternatives,combinations, modifications and variations are apparent to those skilledin the art. Accordingly, the preferred embodiments of this invention, asset forth above are intended to be illustrative only, and not in alimiting sense. Various changes can be made without departing from thespirit and scope of this invention. Combinations of the aboveembodiments and other embodiments will be apparent to those of skill inthe art upon studying the above description and are intended to beembraced therein. Therefore, the scope of the present invention isdefined by the appended claims, and all devices, processes, and methodsthat come within the meaning of the claims, either literally or byequivalence, are intended to be embraced therein.

What is claimed is:
 1. A partially tracked utility vehicle having achassis comprising: front wheels; a trailing link suspension comprising:a trailing link having a first end pivotably connected to said chassisand a second end pivotably connected to a walking beam at a walking beampivot; a shock having a first end pivotably connected to a tension shaftand a second end pivotably connected to said trailing link; said walkingbeam further comprising a plurality of axle mounted bogey wheels forengaging a track of said partially tracked utility vehicle; a sprocketmounted to a traction drive of said partially tracked utility vehiclefor engaging and providing rotational power to said track; and anactuator attached to said chassis, said actuator having a shaftpivotably connected to said tension shaft and configured to rotate saidtension shaft.
 2. The partially tracked utility vehicle as recited inclaim 1 further comprising front wheels having a steerable axle.
 3. Thepartially tracked utility vehicle as recited in claim 2, wherein saidsteerable axle is synchronized with said traction drive of said track toemulate Ackerman Steering geometry.
 4. The partially tracked utilityvehicle as recited in claim 1, wherein the rotation of said tensionshaft increases or decreases the tension of said track tracks.
 5. Thepartially tracked utility vehicle as recited in claim 1, wherein therotation of said tension shaft increases or decreases a height of saidpartially tracked utility vehicle.
 6. The partially tracked utilityvehicle as recited in claim 1, wherein said shock is configured to actas a lock-out member.
 7. The partially tracked utility vehicle asrecited in claim 1, wherein said walking beam pivot of said walking beamis biased toward a front or a rear of said partially tracked utilityvehicle.
 8. The partially tracked utility vehicle as recited in claim 1,wherein said shock is comprised of at least one of a coil, a leaf or atorsion spring; wherein said shock is mechanical, hydraulic, and/orpneumatic.
 9. The partially tracked utility vehicle as recited in claim1, said partially tracked utility vehicle further comprising anattachment boom assembly having a boom and an attachment interface, saidattachment boom assembly being pivotably attached to said chassis. 10.The attachment boom assembly of claim 9 wherein said boom has a firstend and a second end, said boom first end is pivotably attached to saidchassis and said boom second end is pivotably attached to an attachment.11. The attachment boom assembly as in claim 9, further comprising atleast one of a lift cylinder or a pitch cylinder; said lift cylinderbeing pivotably mounted between said chassis and said boom, said pitchcylinder being pivotably mounted between said boom and said attachmentinterface. 12-65. (canceled)
 66. The partially tracked utility vehicleas in claim 1, wherein said partially tracked utility vehicle is autility machine.
 67. The partially tracked utility vehicle of claim 66,wherein said utility machine is a zero turn mower or a zero turntractor.